1. Field of the Invention.
The present invention relates to a double walled metal chimney having an inner flue wall and outer casing wall, and more particularly but not by way of limitation, to an expansion and length adjustment joint for joining chimney sections.
2. Brief Description of the Prior Art.
Heretofore, there have been a number of different types of double walled metal chimneys with expansion joints, such as the expansion joint described in U.S. Pat. No. 4,029,343 to Stone. This expansion joint, while appearing similar to the present invention, uses an annular gasket supported by, and in sealed engagement with, an inner wall end portion. This joint does not provide the advantages of having a separate gasket retaining collar as described herein. Also, U.S. Pat. No. 1,824,422 to Badger, U.S. Pat. No. 2,850,264 to Grable, U.S. Pat. No. 3,208,539 to Henderson, U.S. Pat. No. 3,427,051 to White et al., U.S. Pat. No. 3,544,135 to Hoerrner, U.S. Pat. No. 3,583,730 to Kozlowski and U.S. Pat. No. 3,902,744 to Stone describe different types of metal chimneys, expansion joints and related metal equipment used in chimneys. None of these prior art patents describes the particularly unique features and advantages of the subject adjustment joint with gasket retaining collar.